Welding and Cutting Safety Safety Unit Lesson 5

Oxy-Fuel Welding & Cutting Oxy-fuel welding and cutting are the most common causes of fires in the welding environment.

Oxy-Fuel Welding & Cutting Oxy-fuel safety precautions: Never light an oxy-fuel torch with anything other than an approved torch lighter. Never point the torch at anything you don’t intend to cut. Never lay a lighted torch down on the bench or work station. If its not in your hands it must be shut down. Check Valves and Flashback arrestors must be installed on all welding and cutting equipment. When cutting or welding, clear the area of combustible materials. Never use oxygen as a substitute for compressed air. Never weld or cut directly against concrete. Skin contact with liquid oxygen can cause frostbite. Inspect welding and cutting equipment before use. Oxy-fuel hoses are different colours for safety: typically, RED for fuel gasses and GREEN for oxygen.

Acetylene Safety Because of the extremely hot flame produced, Acetylene gas is the most common fuel gas used for welding and cutting. Acetylene gas is extremely unstable and can explode easily. Because of this acetylene must remain at pressures below 15 pounds per square inch (psi). Acetylene cylinders are filled with liquid acetone and a porous material to increase the stability of the acetylene. Acetylene cylinders must be used in the upright position to prevent the liquid acetone from escaping. If the an acetylene cylinder has been tipped over, stand it up and wait at least one hour before use. If the liquid acetone is withdrawn it will gum up in the regulator and check valves and decrease the stability of the acetylene.

Oxygen Safety Oxygen is a colorless, odorless, and tasteless gas that supports combustion. When combined with a burning material, pure oxygen will cause the fire to flare up and burn out of control. When mixed with a fuel gas oxygen produces the high temperature flame required for cutting and welding.

Cylinders The cylinders used to store compressed gasses need to be handled, transported and stored with special considerations. Oxygen and fuel gas cylinders must be stored separately. The storage areas must be separated by at least 20 feet, or by a five foot high wall with a half hour burn rating. Inert gas cylinders may be stored separately or with oxygen cylinders. All cylinders must be stored in the vertical upright position with protective caps firmly in place. Cylinders should be secured with chains or another device at all times so they cannot be knocked over accidentally. Storage areas must be located away from stairwells, doorways and halls so they do not block exit. Storage areas must also be located away from any potential sources of heat or flame.

Cylinders Oxygen and welding gasses are stored in cylinders at extremely high pressures. A fully charged oxygen cylinder holds approximately 2200 psi at 700 F. Oil should never be used on any gas cylinder connections. Fuel gas cylinders and connections have left handed threads to prevent the use of incorrect regulators or hoses. Soapstone can be used to mark empty cylinders with MT on the top. Empty cylinders should be stored separately from full cylinders.